A dynamic optimization control approach of life cycle energy saving for heat exchanger network with bypasses

In order to achieve sustainable energy saving of heat exchanger network in the life cycle, bypasses were set in the network to increase its control degree of freedom, while a certain margin was designed to provide operating space of optimal control. To better use bypass adjustment and margin of operating space, an optimal control approach method based on dynamic model of heat exchanger network was presented and combined with existing conventional control loop, not only expanding the feasible region of optimal control, but also meeting the accuracy requirements of the original conventional control loop. The cumulative cost minimization of heat exchanger network within a certain period was considered as the objective function, while considering the impact of disturbances on heat exchanger network. To meet the process conditions, the best bypass opening in the life cycle was solved in order to achieve sustained energy saving of heat exchanger network. Closed-loop correction, iterative and rolling implementation were adopted, and optimization was based on actual conditions. A global sub-optimal solution could only be arrived at every turn. However, the actual control result could achieve the optimum. Finally, a refinery's crude oil heat exchanger network was treated as the specific study object, illustrating the effectiveness and application prospect of the presented method. © All Rights Reserved.